Signaling system



Jan 26, 1932. E, DT 1,842,722

SIGNALING SYSTEM Filed April '7. 1928 Z SheetS-Sheet 1 n IL" A TTORNE Y.

Jan, 26 1932. E. E. KLEINSCHMIDT SIGNALING SYSTEM Filed April 7. 1928 2 Sheets-Sheet 2 Q/MQW A TTORNE Y.

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Patented Jan. 26, 1932 UNlTED STATES PATENT OFFICE EDWARD E. KLEINSC'HMIDI, 03E CHICAGO, ILLINOIS, ASBIGNOR 'IO TELETYPE GOR- T'ORA'IION, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE SIGNALING SYSTEM Application filed April '7, 1928.. serial No. 268,239.

This invention relates to signaling systems and is particularly adapted for use in connection with printing telegraph systems in which the signals transmitted are distorted t and altered in wave shape and the received signals are too weak for accurate reception at high speed and where the voltage at the transmitting end cannot be increased due to practical insulation limits, or where signals are necessarily comparatively weak as for example on cable carrier frequency, or radio circuits. I

Un cable circuits of the character mentioned it has been the practice to use Gulstad vibrating relays comprising generally a polarized relay with three windings which are termed line windings opposing windings and accelerating windings. The two latter windings are included in a vibrating circuit comprising a battery, a relay tongue, contacts and adjustable condensers and resistances. Tn practice the relay tongue by adjustment of the resistances and condenser oi the vibrating circuit, is caused to vibrate at a slightly greater frequency than the dot frequency transmitted from the distant station.

To obtain the best results with a relay of this type requires adjustment of the vibrating circuit so that the frequency of vibration exactly corresponds to the frequency of the signal transmitted from the distant station and to make the wave form re-transmitted by the vibrating relay approximately coincide with the initial wave form of the received signals but owing to the efi'ect of temperature, extraneous disturbances and disturbances resulting from imperfect balance of duplex bridges, it is a practical impossibility to operate such telegraph circuits in this manner.

it has accordingly been proposed to approximate the desired condition by providing auxiliary QlBClllL'Q-I'GSPOIlSlVG devices or relays constructed and arranged so that the frequency of vibration of a receiving vibrating relay is automatically maintained in synchronism with the transmitting and receiving mechanism by controlling the energization of the vibrating relay winding jointly through energization of the auxiliary electromagnetic means and a receiving distributor maintained in synchronism with the transmitter. I I

The use of distributors, however, necessitates the usual synchronizing means complicating the apparatus and in addition tends to distort the received Wave shape.

Accordingly, an object of my invention is to provide improved means for operating a telegraph receiver and particularly printers over signaling circuits in which the received signals are ordinarily weak or considerably attenuated.

Another object of my invention to up.

crate a telegraph printer in accordance with impulses generated at a transmitting station but not impressed on the signaling circuit connecting the transmitting and receiving stations.

Still another object of my invention is to provide means for preventing the non-syn chronous operation of the telegraph printer at the receiving station.

The Gulstad vibrating relay has been found to distort the received waves due to its mass in the armature which due to its inertia cannot be maintained accurate in its operation. Accordingly a further object of my invenion is to adopt inertialess apparatus such as vacuum tubes for operation in response to greatly attenuated signals.-

Further objects of the invention are such as may be attained by utilization of the various combinations, sub-combinations and principles hereinafter set forth and defined by the terms of the appended claims in the various other relations in which they are obviously adaptable.

Referring to the drawings:

Figure 1 is a circuit diagram showing a preferred embodiment of the invention with vibrating circuits arranged at both the transmitting and receiving ends as applied to a line wire circuit.

Figure 2 is a circuit diagram showing a modified form of the invention in which tuning forks are employed at the transmitting end in lieu of the vibrating circuits.

My invention comprises an arrangement in which similar oscillating circuits are provided at both the transmitting and receiving stations electrically interlocked so that they oscillate in synchronism. The oscillating circuit at the transmitting station operating jointly with a tuning fork controls the rate of transmission of the code combinations of impulses so as to maintain synchronism between the signals and the oscillatory circuit at the receiving station. The tuned circuit at the receiving end is electrically tied in with that at the transmitter to oscillate in synclntnism therewith and repeat impulses to a printer jointly controlled by the oscillating circuit and a tuning fork. This operation will be more evident from the detailed description which follows:

Referring now more particularly to F igure 1, a transmitting station A is connected to receiving station B by means of conductors 1 and 2, the conductor 2 being connected to the mid-point of battery 3 at station A. The negative side of the battery 3 is connected over conductor 4 to one side of a condenser 5, the other side of which is connected over conductor 6 and resistance 7 to the midpoint of the battery 3. This same side of the condenser 5 is also connectedto the negative biasing battery 8 which is connected to the grid of a suitable three element vacuum tube 9 comprising the usual heated filament, grid and plate. The battery 8 normally maintains the voltage of the grid of vacuum tube 9 negatively biased to prevent any flow of current in the plate circuit under normal conditions as is well understood 'in the art.

Condenser 5 and resistance 7 are, it will be noted, connected across part of the battery 3 so that under proper conditions to be described hereinaiter the condenser 5 is charged, the potential on that side of the condenser connected to the battery 8 being positive. Following such a charge the voltage of the condenser approaches approximately that of the charging portion of battery 3 and finally this voltage becomes greater than the negative bias of the battery 8 with the result that the voltage of the grid becomes positive and current flows in the plate circuit.

The plate circuit of the amplifying tube 9 is connected over conductor 10 to the winding 11, the oppositeterminal of which is connected to the midpoint of the battery 3 over conductor 12. Relay 11 is provided with an armature 13 connected over conductors M and 4 to one side of the condenser 5, and a spring contact for the armature 13 connected over conductor 15 to the opposite side of condenser 5. When therefore the armature 13 engages its front contact following the energization of the winding 11, the condenser 5 is short circuited over the armature 13 and conductors 14 and 15. This provides a discharging path for the condenser 5 for a period following the interval of charging in the manner to be described in detail hereinafter.

A second vacuum tube amplifier 19 comprising a heated filament, grid and plate similar to the tube 9 is connected in a circuit electrically symmetrical with tube 9 as will be noted from the description following. The grid of the tube 19 is normally negatively biased by a battery 20 so that no current flows in the plate circuit of the tube. The positive terminal of biasing battery 20 is connected to a condenser 21, the other terminal of which is connected to the midpoint of battery 3.

Connected intermediate the condenser 21 and the battery 20 is one terminal of a resistance 22 the opposite terminal of which is con nected to the positive side of the battery 3.

The terminal of the condenser 21 connected to the midpoint of battery 3 is also connected over the conductor 12 to the armature 23 of winding 24 connected in the plate circuit of tube 19 over conductor 25 and the contact of armature 23 is connected over conductor 26 to the opposite terminal of condenser 21. In the position shown with armature 23, which, it will be noted is mechanically connected to armature 13 and moves therewith in engagement with its contact and the condenser 21 is therefore short circuited over conductors 12 and 26 and accordingly this condenser cannot be charged at this time.

It will be evident from the above description that at the instant when condenser 21 is short circuited, condenser 5, on the other hand, is being charged from battery 3 over a circuit from the midpoint of the battery 3, through resistance 7 and conductor'6, the condenser 5 and over conductor 4: to the negative side of battery 3 inasmuch as condenser 5 is not short circuited at armature 13, which is now in disengagement with its contacts. As a result of this charging circuit, the positive charge on that plate of the condenser 5 adjacent the battery 8 will become sutficient to balance the voltage of battery 8 and to make the grid positive.

When fully charged, the voltage of condenser 5 will be substantially equal to the po tential of the battery 3 and as the potential upon the grid of tube 9 is carried beyond the knee of the tube characteristic curve, current will begin to flow in the plate circuit as is well understood in the art. This circuit is completed through the winding 11, conductor 12, mid-point of battery 3, conductor 4, and the filament of tube 9. Energization of winding 11 will attract armature 13 into engagement with its spring contact and as a result a circuit is established from one side of the condenser 5 over a conductor 14, armature 13 and conductor 15 to the other side of the condenser and the charged condenser 5 will therefore be discharged over this path. If desired, a relay may be inserted in the circuit including the condenser 5 so as to operate upon the discharge to close armature contacts which are equivalent to those operated by relay 11 thus relieving the relay windings l1 and 24 of the operation of armatures other than armatures 13 and 23. A resistance may, if desired, be inserted in the'condenser short circuit for slowing down the discharge operation.

lit will be seen that following the operation of armature 13 to engage its contact, tube 9 and its associate circuit have now been rcndered non-operative. No charge can be built in the condenser 5 at this time, this condenser being short circuited over the armature 13 as traced above. Bias battery 8 therefore maintains the grid of tube 9 highly negative and this tube ceases to draw plate current for the time being.

The armatures 13 and 23 being mechanically connected together are moved together so that when armature 13 was moved to on gage its contact, armature 23 disengaged its contact and accordingly the short circuit for condenser 21 is removed and this condenser new receives a charge from battery 3. An identical cycle of operation thereupon occurs with respect to the tube 19, that is to say, condenser 21 at this time receives a charge at a rate determined by the resistance 22, the charging circuit being completed through the right hand portion of battery 3 and over resistance 22 to the upper plate of condenser 21 and from the lower plate to the mid-portion of battery 3. the by-passing circuit for condenser traced above being opened at armature 23.

When condenser 21 attains its maximum charge the negative bias impressed upon the grid of tube 19 by the biasing battery 20 will be overcome and current will flow in the plate circuit of tube 19, this circuit being completed over the conductor 25, through the winding of the relay 2% over conductor 26 to the positive side of the battery and from the midpoint of the battery 3 to the filament of the tube 19. The armature 23 will thereupon be moved to ire-engage its contact and the condenser 21 will discharge over the conductors 12 and 26 and the front contact of armature 23.

it will now be apparent that if condensers 5 and 21., tubes 9 and 19 and resistances 7 and 22 are similar in characteristics, equal intervals will be taken by the condenser to attain their maximum charge and an oscillating system of a constant frequency will be obtained. That is to say, armatures 13 and 23 will oscillate back and forth, and the period of time intervening between the reversals of the position of the armatures will be determined by the value of the resistances and the capacity of the condensers. Normally this operation will continue while alternate marking and spacing impulses are transmitted over the signaling line in a manner to be described in detail hereafter.

The relay comprising windings 11 and 2A alternately engaged, these armatures oscillate between their alternate positions for purposes to be described in detail hereafter.

The transmitter 29 is controlled by a tuning fork 33 secured to a fixed support 34 and is provided with tines 35 upon which are secured adjustable weights 36 for the purpose of regulating the vibration frequency of the forks. Secured to the tines 35 are insulated contacting members 37 which as the tines 35 spread and come together, permit its contacts to open and close. Connected in series with these contacts is magnetic drive magnet 38 for controlling the vibrations of the tines 35.

To start the fork 33 into vibration the tines are spread by hand and released. The movement of the tines outward closes a circuit through the magnet 38 over the contacts 37 and battery 3. Energization of mag net 38 attracts the tines and draws them inward. As the tines move inward, contacts 37 separate 0 open the circuit and Clo-energize the magnet 38. In this manner, the fork is kept in vibration at a uniform and predetermined rate equivalent to the operation of the oscillating circuit.

Contact operating members 39 secured to the tines 35 of the tuning fork opens and closes its contacts 40 connected in the electrical circuit of the magnet 41. Magnet 41 as it alternately energizes and de-energizes operates an escapement 42 acting on the escapement wheel 43 secured to the pin barrel shaft 44 of the transmitter 28. With the tuning fork vibrating in the manner described above, the pin barrel 44: is stepped around in unison or synchronism with the operation of the oscillating circuit described above. As described in the Patent st -1,567,599 the contactor 28 is moved from one to its alternate contact in accordance with the code set up as the pin barrel rotates, to transmit impulses for operating the receiver in a manner to be described, in detail hereinafter. At the receiving station B, apparatus substantially equivalent to that disclosed at the transmitting station are employed. The grid of a three element amplifier tube isconnected to the terminal of a biasing battery 51 which maintains the grid of this tube normally at such a negative potential as to prevent the flow of current in the plate circuit of the tube. The positive terminal of the battery 51 is connected to one side of a condenser 54 the opposite plate of which is connected to the nega tive side of the battery. Resistance 55 is connected to the midpoint between condenser 54 and battery 51 and to the midpoint of battery 53. The plate of the three element tube 50 is connected to the winding 56 and thence over the conductor 57 to the midpoint of the battery 53-.

It will be noted that the condenser 54 is arranged to normally receive a charge on its plate from the midpoint of the battery 53 through the resistance 55. A short circuit path is, however, provided for condenser 54 over conductors 48 and 49 and armature 60 of relay 56 when this armature engages its contact. As shown, however, with armature 60 disengaged from its contact, a charge is collected on the condenser 54 from the battery 53.

Vacuum tube 61 is a standard three element tube, the grid of which is connected to ,a battery 62 which normally biases the grid negatively sufliciently to prevent any flow of current in the plate circuit of the tube 61. The opposite terminal of the battery 62 is connected to one plate of a condenser 63 the opposite plate of which is connected to the midpoint of the battery 53. A connection is made intermediate the condenser 63 and the battery 62 including the resistance 64 to the positive side of the battery 53. The same side of the condenser 63 is connected over conductor 65 to the contact of armature 66 which in turn is connected over conductor 67 to the opposite plate of the condenser 63.

When the armature 66 is not in engagement with its contact, a circuit is completed from one to the other plate of the condenser 63 including the resistance 64 and a portion of the battery 53 and the condenser is charged in a manner to overcome the negative bias of the battery 62. When the armature 66 engages its contact, a short circuit is .provided between the two plates of the condenser 63 which thereupon discharges.

A winding 68 connected by means of conductor 69 to the plate of tube 61 and by means of conductor 7 O to the positive side of battery 53, controls armatures 60, 66, 71 and 72 which are mechanically connected to each other and move together. Armature 71 is connected to the signaling line 1 and as it vibrates under joint control of windings 56 and 68 alternate positive and negative polarity from battery 53 is impressed on the signaling line over conductors 71 and 49. Armature 72 controls a circuit for the magnet 73 which operates a pin barrel or cam shaft 74 of a receiving printer as shown in copending application Serial Number 741,- 578 filed October 4, 1924.

The pin barrel 74 is rotated by an escapement wheel 75 mounted upon and controlling the shaft 74. An escapement 76 actuatcd b magnet 77 operates the esc-apement wheel 5. The magnet 77 is connected in an electrical circuit with the insulated contactor 78 secured to the tines 79 of a tuning fork. The tuning fork is secured to a fixed support 80-and is provided with adjustable weights 81 for the purpose of regulating the vibration frequency of the forks. A magnet 82 connected to an insulated contact member carried on the tines 79 maintains the forks in vibration. The forks are started by first spreading the tines by hand and then releasing them. When the tines spread a circuit is completed for magnet 82 from battery 53 over conductor 83 through contactor 84, magnet 82 and conductor 85 to the battery 53. Magnet 82 is energized and draws the tines inward to break contact 83.

It will be noted from the above description that the operation of the two tubes 50 and 61 is substantially the same as that described in connection with the receiving station. In the arrangement shown, the winding 56 being de-energized and the armature 50 in disengagament with its contact, the condenser 54 is being charged over a circuit including the resistance 55 and the left end portion of the battery 53. As the condenser 54 becomes charged positively and approaches the voltage of the left half portion of battery 53, the negative bias on the grid of the vacuum tube 50 produced by the biasing battery 51 is overcome and the current begins to fiow in the plate circuit of the tube 50, the circuit including the conductor 55, winding 56, conductor 57 and left end portion of the battery 53 to the filament of tube 50. Upon energization of the relay 56 over the circuit traced above, the armature 60 is brought into engagement with its contact and a circuit for discharging condenser 54 is completed over the conductor 49, armature 60 and the conductor 48 so that the voltage of the grid is again negatively biased by the battery 51.

The armatures 50, 71, 72 and .66 are mechanically connected so that when armature 60 moves into tngageinent with its contact, the armature 66 disengages its contact and the condenser 63 which formerly was short circuited, now receives a charge from the right end portion of the battery 53 through the resistance 64. After an interval of time, the condenser 63, which it will be noted as in the case of the other condensers is connected to the battery in a manner to put the positive charge on the plate adjacent the grid, is sufficiently charged so that the negative bias of the battery 62 is overcome and the grid receives a positive charge, suflicient to permit the fiow of current in the plate circuit. When the grid has been sufficiently charged, there is a sudden flow of current in the plate circuit through the winding 68 and through the right end portion of battery 53 to the filament of the tube and the winding 68 is energized, short cireuiting the condenser 63 at armature 66 and simultaneously opening the short circuit of condenser 54 at armature 60.

lt will be recalled that the signaling line 1 is connected to the armature 27 through contact member 28 at the transmitting station and to the armature 71 at the receiving station and that the signaling line 2 forming the return circuit for the system, is connected at the midpoint of the batteries at the two ends of the line. It will be obvious of course that a ground return circuit may be used in place of the second signaling line as is more usually the practice in telegraph systems. although for purposes of illustration, a return signaling line is disclosed.

/Vith the apparatus operating normally the condenser 21 at the transmitting station A, and the condenser 63 at the receiving station B are short circuited simultaneously as shown in the drawings. Simultaneously condenser 5 at the transmitting station A and condenser 54 at the receiving station B are being charged by their respective batteries.

At this time no impulse is bein transmitted over the lines 1 and 2, the slgnaling tine 1, it will be noted, being connected at the transmitting station over the armature 27 in engagement with its right contact and the conductor 14 to the negative side of the battery 4, while at the receiving station the conductor l is connected over the armature 71 in engagement with its right contact to the negative side of the battery 53 over conductor 49. The potentials of these two batteriesare therefore at this instance bucking each other so that no current is flowing in the signaling circuit. WV hen the armatures 27 and 71 at the transmitting and receiving station respectively upon their next operation move into engagement with their contacts on the left, the signaling line 1 is connected over to the positive side of the battery 4 at the transmitting station over conductor 26, while at the receiving station the signaling line 1 is connected to the positive side of battery 53 conductor 71', so that again the voltages of the batteries are bucking. In this manner, as the oscillating circuits normally operate, the signal line is alternately connected to the negative and positive side of batteries at the transmitting and receiving stations, and in each instance the batteries are connected in bucking relation, so that no current normally flows over the signaling line.

The manner of transmitting code signals will now be described. "With the apparatus operating normally, the winding 11 at the transmitting station, the winding 56 at the receiving station are energized simultaneous- 1y to move the armatures 13, 27, 30, 31 and 23 at the transmitting station, and armatures 60, 71 and 72 and 66 at the receiving station to their left hand position and after an interval of time, in a manner which has been described in detail above, the winding 24 at the transmitting station and winding 68 at the receiving station are energized to restore their respective armatures to the position shown. Simultaneously the tuning fork 33 at the transmitting station and the tuning fork 79 at the receiving station vibrate to'rotate their respective pin barrels 44 and 74, the tuning forks, it Wlll be understood, operating in synchroni'sm with the tuned circuits so that for each operation of a winding 11 or 24 at the transmitting station 56 or 68 at the receiving station, the pin barrel 44 or 74 is rotated one step. While the code bein transmitted comprises alternate marking an spacing impulses, the tape transmitter at. the receiving station is so perforated as to maintain the contactor 28 in the position shown. At the receiving station as the Winding 56 and 68 alternately energize, armature 72 engages and disengages these contacts and alternately completes an energizing circuit for the relay 7%} which controls the selector through the pin barrel 74 in the manner described in the above referred to patent. As long therefore as the successive impulses are alternately marking and spacing signals no actual impulses are transmitted over the signaling line and the printer will nevertheless operate as if a succession of impulses of alternate marking and spacing character were received. If, however, the code being transmitted calls for successive spacing impulses in place of the normal alternate marking impulse, the contactor 28 will be moved to engage its right hand contact.

It will be assumed that this occurs the instant when the apparatus is in the condition shown which is the spacing period inasmuch as no circuit is at this time completed for the magnet 7 3 for operating the selector in accordance with a supposed received spacing impulse. It will be assumed that the succeeding impulse is to also be a spacing impulse instead of the marking impulse which it would normally be.

To reverse the impulse to be transmitted the contactor 28 is moved to engage its right hand contact. A circuit is thereupon completed from the positive side of battery 3 over a conductor 26 to the contact and armature 30 over the contactor 28, conductor 1, armature 71, in engagement with its right hand contact, conductor 49 to the negative side of battery 53 and over conductor 2 through the right hand portion of battery 3. This circuit, it will be noted short circuits the condenser 54 which would otherwise be receiving a charge from the left half of battery 53 at this time. At the same time a short circuit is provided for the condenser 5 from the midportion of battery 3 over a circuit including conductor 46, contactor 47, armature 32 and over conductor 14 to the left hand side of the battery 3.

' station and condensers 54 and 63 at the receiving station are short circuited at this time so that no charging and accordingly no further oscillation takes place. At the same time the tuning forks at both stations continue vibrating and the magnet 72 continues to step the pin barrel 74 .to its next position but since the relay will be energized and armature 72 disengaged, the spacing condition will continue and the magnet 73 will not energize for the succeeding position of the pin barrel although normally, as explained above,

armature 72 would have been in engagement at this time with its contact to energize the magnet 73 for operating the pin barrel in accordance with the receipt of a marking inipulse. If now the succeeding impulse is still a spacing impulse, the contactor 28 will continue to be maintained in engagement with its right hand contact. If, on the other hand, the impulse is a marking impulse then the armature contactor 28 will be restored to its original position, the normal conditions will then again be obtained and condensers 5 at the ofiice and 54 at the sub-station will again tend to charge to oscillate their respective sets of armatures in the manner described above. Armature 72 will thereupon move into engagement with its contact to complete an energizing circuit for the magnet 73 for a marking operation. Itwillbe evident from this description that normally no impulses are transmitted over the signaling line to operate the printers in accordance with successive marking and spacing impulses and that in the event that code combinations being transmitted comprise a succession of marking impulses, it is only necessary to short circuit the battery connecting the stations which thereupon results in bringing the two local oscillating circuits to a stop for performing the printing operation. Inasmuch as short circuiting the batteries provides a much more positive action that can be obtained in the transmission of a signaling impulse, it is evident that the system is particularly desirable in the case of the transmission of long impulses where attenuation of the received signal occurs.

' Although with the circuits arranged in this manner, the vacuum tubes, condensers and resistances can be so calibrated as to provide perfect oscillation so that failure of synchronism is substantially impossible, provision has been made for taking care of a condition in which one of the oscillating circuits falls out of step with the other. It will be assumed for purposes of illustration that with the circuit as shown at the transmitting station, the apparatus at the receiving station is operating incorrectly or one step out of synchronism with that at the transmitting station and as a result the armature 13 is then in engagement with its contact instead of disengaged as shown. With the armature at the receiving station in engagement with the contact .on the right, the condenser 63 is-short circuited as has already been described above. At the transmitting station with the armature 13 in engagement with its contact, the condenser 5 is short circuited over the conductor 14, armature 13, and conductor 15. With this condition, a charging circuit would normally be completed for condenser 21 at the transmitting station since armature 23 is not engaging its contact and a charging circuit would normally be complet- \ed for condenser 54 at the receiving station inasmuch as armature 60 is not engaging its contact. These condensers, however, will not receive a charge at this time as a short circuit will also be completed therefor from the positive side of the battery 3 at the transmitting station and the negative side of the battery 53 at the receiving station over signaling lines 1 and 2, the circuit including conductor 26, left contact and armature 27, contact member 28, conductor 1, armature 71, in engagement with its right hand contact over the conductor 49 through the left end portion of the battery 53, over conductor 2, to the midpoint of the battery 3, and through the right end portion of the battery 3 from negative to positive to conductor 26. Inasmuch as condenser 54 can be charged only from the left end portion of battery 53 which, however, is short circuited over the circuit astraced above, this condenser will not be charged since by providing proper constants, the line will act as a short circuit for thecondenser. Similarly at the transmitting station, inasmuchas condenser 21 is connected across the right portion of battery 3 which is short circuited over signaling line 1, this condenser will not be charged.

As a result, since as described above, neither the condenser 5 or 21 at the transmitting station nor the condensers 51 or 63 at the receiving station are being charged, the apparatus will be brought to a stop and no further operations can occur until the apparatus is brought back into synchronism. Although provision is thus made for taking care of nonsynchronous conditions it is evident that normally no such condition can exist with the apparatus of the character disclosed in the operating condition.

Referring now more particularly to Figure 2, it will be noted that the oscillating circuit employing the vacuum tubes and condensers at the transmitting station is replaced by a tuning fork which comprises a transmitting fork 90 secured to a fixed support 91 and provided with tines 92 and 93 to whlch are secured adjustable weights 94 and 95 for the purpose of regulating the vibration rate of the fork. Secured to tines 92 and 93 1 are insulated contact operating members 96 and 97 which as the tines 92 and 93 spread andcome together, alternately and simultaneously close and permit fixed contacts 96 and 97 to open and close.- Connected in series with these contacts is a drive magnet 08 and a battery 99. To start the fork into vibration, the tines are stressed by hand and released. The movement of the tines outward closes a circuit through magnet 98 which then attracts the tines and draws them inward. As the tines move-inward, the con-v tacts 96 and 97 separate and (lo-energize the magnet 08. In this manner the fork is kept in powerful vibration at a uniform and predetermined rate.

Secured to the ends of tines 92 and 93 are insulated contact operating members 100 and 101. Member 100 alternately and successively opens and closes contacts 102, 103, 104 and 105. Contacts 102 and 105 are connected to transmitting tongues 106 and 107 of polarized transmitting relays 108 and 109 and contacts 103 and 104 are connected to line conductor 1. Member 101 alternately and successively opens and closes contacts 110, 111, 112 and 113. Contact 110 is connected to the winding transmitting relay 108 and contacts 111 and 112 are connected by conductor 114 through transmitter control magnet 115 to the midpoint between connected batteries 116 and 117. The outer terminal of batteries 116 and 117 are connected through resistances 118 and 119 to fined contacts 120 and 121. In the form shown, magnet 115 actuates armature or escapement member 122 which controls escapement wheel 124. Escapement wheel 124 is mounted upon and controls the rotation of a pin barrel or cam shaft 125. Tongue 126 operates in accordance with code combinations to be transmitted under control of the pin barrel 125. It will be understood, however, that the transmitter is not limited to my improved pin barrel type shown in the patent hereinbefore referred to, but any of the single contact combination code transmitters may be adapted for use in the system by timing the impulses of the transmitted signals from the transmitting fork. Tongue 126 is actuated between contacts 120 and 121 and completes energizing circuits through. relays 108 and 109, and batteries 116 and 117, causing tongues 106 and 107 to engage contacts 130, 131, 132 and 133 respectively applying code combinations of positive and negative impulses, batteries 134 and 135, over resistances 136 and 137, contacts 102, 103, 104 and 105 to line 1, as described in detail in application Serial No. 5,740.

At the receiving station, substantially the same arrangement of vacuum tubes and con densers is employed as illustrated in connection with Figure 1, and like parts have therefore been given the same numerals. The sig naling line 1 is connected to the contacts 103 and 104 of the tuning fork 90 at the transmitting station and to the armature 71 at the receiving station. The negative side of battery 53 at the receiving station is connected over to one plate of the condenser 54, the other plate of which is connected over the resistance to the mid-terminal of the battery 53. As disclosed therefore, this condenser will tend to be charged by the left portion of the battery 5?. The same side of the condcns'cr 54 is connected through the negative biasing battery 51' to the grid of a three element tube 50, which by reason of the negative bias of the grid of the tube is normally nonoperating, no current flowing in the'plate circuit. The terminal of the condenser 54 which is connected to the negative side of the battery 53 is also connected over conductor 49 to the armature of the relay 56, the contact of which is connected over conductor 48 to the opposite terminal of the condenser 54. \Vhen the relay 11 is energized, the condenser 54 is short circuited over conductors 49 and 48 and the armature 60 in engagement with its contact, and will discharge over this circuit. The relay 56 energizes in a manner described in detail over the conductor 55 in cluding theplate of the three elements, tube 50 and conductors 67 to the mid-point of the battery 53 and over the left portion of the battery 53 to the filament of tube 50. A similar arrangement of the three element tube 61 is disclosed in which the grid is negatively biased by means of a battery 62 so as to pre vent any normal flow in the plate circuit and conductor of the three-element tube 19. One plate of condenser 63 is connected to the mid-terminal. of the battery 53 and the'opposite plate is connected to the battery 62. This same plate of the condenser 63 is connected to resistance 64, the opposite side of which is connected to the positive side of the battery 53. With the normal by-passing circuit for the condenser 63, including conductors 65 and 67 and armature 66 open, the condenser 63 is charged by the battery 53 to an extent sufficient to overcome the biasing voltage of battery 62 with a resultant flow of current in the plate circuit of the three element amplifying tube 61. When, however, the armature 66 is, as shown, in engagement with its contact, the condenser 63 is short circuited over conductors 65 and 67 and armature 66 in engagement with its contact, and as a result will discharge its charge. The relay 68 is connected to the plate of the tube over conductor 65, and over conductor 71 to the positive side of the battery 53 and when erergized operates armatures 60, 71, 72 and 66, the latter for short circuiting the condenser as described above.

Electrically interconnected with tuned circuits described above, is a vibrating fork, the tines 7 9 of which vibrate back and forth in the well known manner described in conneclion with Figure 1. Since the tuning fork tines 7 9 vibrate in synchronism with the electrical oscillations described above, the pin barrel will he stepped by magnet 77 in unison and magnet 73 will alternately energize and de-energize in :urcordance with alternate marking and spacing impulses.

The ren'iaining portions of this circuit are identical with those described in connection with Figure 1 and need not therefore be described in detail again. The operation of this apparatus will be now described.

Normally as the tuning fork tines 92 and 93 vibrate, a circuit is first completed over battery 116, resistance 119, contact 120, contactor 126, through the winding of the polar relay 100. over the contact 113 and 112 when the tines are spread apart over conductor 111 to the relay 115 to the battery 116. \Vhen the tines come together, the same circuit as traced above is completed except that from contact 126 the circuit is completed through the winding of the polar relay 108 and over the contact 110 and 111 to conductor 114, magnet winding 115 and battery 116.

Normally the armatures. 106 and 107 are maintained in-engagement with their right hand contact and alternate positive and negative polarities are impressed upon the signaling line 1 from the battery 134 when the tines are spread apart over the contact 131, armature 106, contacts 102 and 103, and over the line 1, and when the tines are to gether from battery 135 to resistance 137, contact 133, armature 107 and contacts 104 and 105 to the signaling line 1. In this manner alternate positive and negative polarities are impressed upon the signaling line similar to that disclosed and described in connection with the oscillating circuits in Figure 1. Simultaneously at the receiving station, the relays 56 and 68 are alternately energized to vibrate their aramatures 50, 71, 72 and 66, and alternate positive and negative polarities from battery 53, are connected to the line 1 in the manner described above. As the armature 72 is vibrated magnet 72' is alternately energized and de-energized to operate the pin-barrel 73 in the manner which has been described in detail above in accordance with the alternate marking and spacing impulses received.

Should the code combinations to be transmitted call for any other than the particular polarity which at that time would normally operate the receiver 72, that is if a marking impulse is to follow a marking impulse to take the place of a spacing impulse, the transmitter contact 126 is operated to its alternate position and an impulse of the opposite polarity is impressed upon the signaling line 1 which thereupon short circuits that portion of the battery 53 at the receiving station which is at that time charging its condenser so as to bring the two electrical circuits to a stop and permit the successive recording of the same character of received impulses. In the illustration shown it will be assumed that the succeeding impulse is to be a spacing impulse similar to that shown. The contact 126 is thereupon moved into engagement with the contacts 121 and an ener 'zing circuit is completed for the polar re ay 109, it being assumed that the tines at this time'are spread apart and a circuit is completed from thebattery 117, resistance 118, contact 121, and 126 through the polar relay 107 and over the contacts 113 and 112 to the conductor 114. Armature 107 is thereupon moved into engagement with its contact 132 and when the tines are spread apart, instead of the positive polarity being impressed'upon the line, an impulse of negative polarity is impressed upon the line from the battery 134 over resistance 136, contact 132, armature 107, contacts 105 and 104 and over the conductor 1. At this time the armature 71 is in en agement with its left hand contact and this circuit is thereupon completed through armature 71 and its left hand contact, over the conductor 71 to the positive side of battery 53 and through to the midpoint over conductor 2 to the mid-terminal of battery at the receiving station. Since at this time the condenser 63 ordinarily would be charging but its portions of the battery 53 is short clrcuited over the circuit traced above, condenser 63 is not charged. Inasmuch as condenser 54 is short circuited over the contact of armature 60, neither condenser is char ed at this time with the result that the vibrating electrical circuit is brought to a stop. The tuning fork, however, continues to vibrate to step the pin barrel 73 from contact to contact and the armature 7 2 being in engagement with the contact, the magnet 72 operates in accordance with continned marking impulses as long as armature 126 is maintained in engagement with its left hand contact at the receiving station.

Although I have disclosed my invention as applied to a telegraph system, it is obvious that the same principles may be employed in the transmission of a carrier signaling system in a low frequency range in which tuning forks are provided for further stabilizing the frequencies generated by the oscillating circuit.

Having described preferred embodiments of my invention, what is desired to be secured by Letters Patent and claimed as new is:

1. A telegraph selective system comprising an electrical oscillating circuit at a transmitting station, an electrical oscillating circuit at a receiving station, said circuits being arranged to oscillate in synchronism and phase with each other and a signaling line connecting said stations.

2. A selective system comprising an electrical oscillating circuit at a transmitting station, an electrical oscillating circuit at a lit elti

till

till

receiving station, said circuits being arranged to oscillate in synchronism and phase with each other, a signaling line connectin r said stations, said oscillating circuits each eing arranged to impress potentials upon said signaling line, of alternate positive and negative polarities.

3. A selective system comprising an electrical os-illating circuit at a transmitting station, an electrical oscillating circuit at a receiving station, means for oscillating said circuits in synchronism and phase with each other, a signaling line connecting said stations, means controlled by said oscillating circuits for impressing potentials upon said signaling line of alternate positive and negative polarities, said polarities being arranged to buck each other while said oscillating circuits are in synchronism with each other.

at. ln a telegraph system, a first electrical circuit a second electrical circuit, means for operating said electrical circuits alternately and in synchronism with code combinations of impulses and means at a remote station for generating said code combinations in synchronism with the alternate operation of said first and second electrical circuit.

5. ln a telegraph system, a first oscillating circuit, a second oscillating circuit, means for operating said electrical circuits alternately in synchronism with received code combinations of impulses, means at a remote station for impressing signals on said line in synchronism with the alternate operation of said first and second electrical circuit, said means being all electrical.

6. ln combination, an electrical circuit, including an electronic tube, a condenser, said condenser being arranged to control the operation of said tube, a second tube and a condenser arranged to control the operation or said second tube, means for alternately charging said first and said second condenser whereby their respective tubes become operative, and means for operating a telegraph receiver in accordance with the operation of said tubes.

'7. ln combination, an electrical circuit, in cluding an electronic tube, a condenser arranged to control the operation of said tube, a second tube and a condenser arranged to control the operation of said second tube, means for alternately charging said first and said second condenser whereby their respective tubes become operative, means for operating a telegraph receiver in accordance with the operation of said tubes, and means for transmitting signaling impulses over said circuit in synchronism with the charging of said condensers.

8. ln combination, an electrical circuit, including an electronic tube, a condenser, said condenser being arranged to control the operation of said tube, a second tube, a condenser arranged to control the operation of said second tube, means for alternately charging said first and said second condenser whereby their respective tubes become operative, means for operating a telegraph receiver in accordance with the operation of said tubes, means for transmitting signaling impulses over said circuit in synchronism with the charging of said condensers, and means at a remote station including equivalent electrical circuits for impressing said signaling impulses on said line in synchronism with the operation of said electron tubes.

9. In combination, a first vacuum tube, a condenser, a second vacuum tube, a second condenser, means for simultaneously charging said first condenser and discharging said second condenser, means responsive to the charging of said first condenser for rendering said first mentioned tube operative, means responsive to the operation of said first tube for discharging said first mentioned condenser and charging said second condenser for rendering said second tube operative, and means responsive to the operation or said tube for operating a printer.

10. lln combination, a first vacuum tube, a condenser therefor, a second vacuum tube, a condenser therefor, means for simultaneously charging said first condenser and discharging said second condenser, means responsive to the charging of said first condenser for rendering said first mentioned tube operative, means responsive to the operation of said first tube for discharging said first mentioned condenser and charging said second condenser, means operative responsive to the charging of said second condenser for rendering said second tube operation, means responsive to the operation of said tube for operating a printer, a remote station, means thereat for stopping the charging of said condensers, a condenser and tube at the remote station, a second condenser and tube at said remote station, means for charging the first condenser and discharging the second mentioned condenser simultaneously with the charging of the first mentioned condenser at the first station and discharging of the second mentioned condenser at the first station, means responsive to the charging of the condenser at the remote station for rendering the first mentioned tube operative simultaneously with the operativeness of the first mentioned tube at the first station, and means responsive to the operation of said tube for discharging said first mentioned condenser and charging said second mentioned condenser simultaneously with the discharging of the first mentioned condenser and the second mentioned condenser at the first mentioned station.

11. The method of signaling over a long cable over which the signals are considerably attenuated which comprises simultaneously impressing a signal condition of positive polarity on the signaling line at both ends of the line thereof followed by the simultaneous impression of a signal condition of negative polarity on the signaling line from both ends, repeating the above cycle of operation durin the signaling period and reversing the po arity impressed from the transmitting end upon the signaling line from that which normally would be impressed at that instance for the transmission of code combination of conditions.

12. The method of signaling over a long cable over which the signals are considerably attenuated and having a battery supply at each end which comprises arranging the batteries in opposing relation for one impulse condition and arranging the batteries in series relation for the alternate signalingconditions.

13. The method of transmitting code combinations of impulses over a long cable over which the signals are considerably attenuated which comprises arranging opposing batteries at both ends of the line for one condition of signaling arranging the batteries of both ends of the line in adding relation for the other condition of signaling and synchronously switching the battery connections at each end of the line.

14. In a signaling system, a first station, a second station, a source of energy at each of said stations and means for signaling which comprises opposing said sources of energy for one condition of signaling and adding said sources of energy for the other condition of signaling.

15. Ina signaling system, a first station, a second station, a source of energy at each of said stations and means for signaling which comprises opposing said sources of energy for one condition of signaling and adding said sources of energy for the other condition of signaling and means for synchronously switching the connections of said sources of energy to said signaling line.-

16. In a signaling system, a transmitting station, a receiving station, a telegraph printing apparatus at each of said stations, a tuning fork at each of said stations, means controlled by said tuning fork for operating said telegraph apparatus, an oscillating circuit at each of said stations, means controlled by said oscillating circuit for operating said tuning fork in synchronism and means for operating said oscillating circuits at each of said stations in synchronism with each other.

- In testimony whereof I afiix my signature.

EDWARD E. KLEINSCHMIDT. 

